diff --git a/src/main/scala/uncore/tilelink2/IntNodes.scala b/src/main/scala/uncore/tilelink2/IntNodes.scala
index 0d46300c..21ddd87f 100644
--- a/src/main/scala/uncore/tilelink2/IntNodes.scala
+++ b/src/main/scala/uncore/tilelink2/IntNodes.scala
@@ -60,6 +60,7 @@ object IntImp extends NodeImp[IntSourcePortParameters, IntSinkPortParameters, In
     Vec(ei.size, Vec(ei.map(_.source.num).max, Bool())).flip
   }
 
+  def colour = "#0000ff" // blue
   def connect(bo: => Vec[Bool], bi: => Vec[Bool], ei: => IntEdge)(implicit sourceInfo: SourceInfo): (Option[LazyModule], () => Unit) = {
     (None, () => {
       // Cannot use bulk connect, because the widths could differ
diff --git a/src/main/scala/uncore/tilelink2/LazyModule.scala b/src/main/scala/uncore/tilelink2/LazyModule.scala
index b18e0e5c..d2bb370b 100644
--- a/src/main/scala/uncore/tilelink2/LazyModule.scala
+++ b/src/main/scala/uncore/tilelink2/LazyModule.scala
@@ -35,7 +35,8 @@ abstract class LazyModule
     val buf = new StringBuilder
     buf ++= "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
     buf ++= "<graphml xmlns=\"http://graphml.graphdrawing.org/xmlns\" xmlns:y=\"http://www.yworks.com/xml/graphml\">\n"
-    buf ++= "  <key for=\"node\" id=\"d1\" yfiles.type=\"nodegraphics\"/>\n"
+    buf ++= "  <key for=\"node\" id=\"n\" yfiles.type=\"nodegraphics\"/>\n"
+    buf ++= "  <key for=\"edge\" id=\"e\" yfiles.type=\"edgegraphics\"/>\n"
     buf ++= "  <graph id=\"G\" edgedefault=\"directed\">\n"
     nodesGraphML(buf, "    ")
     edgesGraphML(buf, "    ")
@@ -48,7 +49,7 @@ abstract class LazyModule
 
   private def nodesGraphML(buf: StringBuilder, pad: String) {
     buf ++= s"""${pad}<node id=\"${index}\">\n"""
-    buf ++= s"""${pad}  <data key=\"d1\"><y:ShapeNode><y:NodeLabel modelName=\"sides\" modelPosition=\"w\" fontSize=\"10\" borderDistance=\"1.0\" rotationAngle=\"270.0\">${module.name}</y:NodeLabel></y:ShapeNode></data>\n"""
+    buf ++= s"""${pad}  <data key=\"n\"><y:ShapeNode><y:NodeLabel modelName=\"sides\" modelPosition=\"w\" fontSize=\"10\" borderDistance=\"1.0\" rotationAngle=\"270.0\">${module.name}</y:NodeLabel></y:ShapeNode></data>\n"""
     buf ++= s"""${pad}  <graph id=\"${index}::\" edgedefault=\"directed\">\n"""
     nodes.filter(!_.omitGraphML).foreach { n =>
       buf ++= s"""${pad}    <node id=\"${index}::${n.index}\"/>\n"""
@@ -62,7 +63,7 @@ abstract class LazyModule
       buf ++= pad
       buf ++= "<edge"
       buf ++= s""" source=\"${index}::${n.index}\""""
-      buf ++= s""" target=\"${o.lazyModule.index}::${o.index}\"/>\n"""
+      buf ++= s""" target=\"${o.lazyModule.index}::${o.index}\"><data key=\"e\"><y:PolyLineEdge><y:Arrows source=\"none\" target=\"standard\"/><y:LineStyle color=\"${o.colour}\" type=\"line\" width=\"1.0\"/></y:PolyLineEdge></data></edge>\n"""
     } }
     children.filter(!_.omitGraphML).foreach { c => c.edgesGraphML(buf, pad) }
   }
diff --git a/src/main/scala/uncore/tilelink2/Nodes.scala b/src/main/scala/uncore/tilelink2/Nodes.scala
index 9a4c0497..34d2be29 100644
--- a/src/main/scala/uncore/tilelink2/Nodes.scala
+++ b/src/main/scala/uncore/tilelink2/Nodes.scala
@@ -15,6 +15,7 @@ trait InwardNodeImp[DI, UI, EI, BI <: Data]
   def edgeI(pd: DI, pu: UI): EI
   def bundleI(ei: Seq[EI]): Vec[BI]
   def mixI(pu: UI, node: InwardNode[DI, UI, BI]): UI = pu
+  def colour: String
   def connect(bo: => BI, bi: => BI, e: => EI)(implicit sourceInfo: SourceInfo): (Option[LazyModule], () => Unit)
 }
 
@@ -42,11 +43,11 @@ abstract class BaseNode
   lazyModule.nodes = this :: lazyModule.nodes
 
   def name = lazyModule.name + "." + getClass.getName.split('.').last
-  def colour = "blue"
   def omitGraphML = outputs.isEmpty && inputs.isEmpty
 
   protected[tilelink2] def outputs: Seq[BaseNode]
   protected[tilelink2] def inputs:  Seq[BaseNode]
+  protected[tilelink2] def colour:  String
 }
 
 trait InwardNode[DI, UI, BI <: Data] extends BaseNode
@@ -109,6 +110,7 @@ class MixedNode[DI, UI, EI, BI <: Data, DO, UO, EO, BO <: Data](
   extends BaseNode with InwardNode[DI, UI, BI] with OutwardNode[DO, UO, BO]
 {
   // meta-data for printing the node graph
+  protected[tilelink2] def colour  = inner.colour
   protected[tilelink2] def outputs = oPorts.map(_._2)
   protected[tilelink2] def inputs  = iPorts.map(_._2)
 
diff --git a/src/main/scala/uncore/tilelink2/TLNodes.scala b/src/main/scala/uncore/tilelink2/TLNodes.scala
index e52b275d..b02c9883 100644
--- a/src/main/scala/uncore/tilelink2/TLNodes.scala
+++ b/src/main/scala/uncore/tilelink2/TLNodes.scala
@@ -19,6 +19,7 @@ object TLImp extends NodeImp[TLClientPortParameters, TLManagerPortParameters, TL
     Vec(ei.size, TLBundle(ei.map(_.bundle).reduce(_.union(_)))).flip
   }
 
+  def colour = "#000000" // black
   def connect(bo: => TLBundle, bi: => TLBundle, ei: => TLEdgeIn)(implicit sourceInfo: SourceInfo): (Option[LazyModule], () => Unit) = {
     val monitor = LazyModule(new TLMonitor(() => new TLBundleSnoop(bo.params), () => ei, sourceInfo))
     (Some(monitor), () => {
@@ -85,6 +86,7 @@ object TLAsyncImp extends NodeImp[TLAsyncClientPortParameters, TLAsyncManagerPor
     Vec(ei.size, new TLAsyncBundle(ei(0).bundle)).flip
   }
 
+  def colour = "#ff0000" // red
   def connect(bo: => TLAsyncBundle, bi: => TLAsyncBundle, ei: => TLAsyncEdgeParameters)(implicit sourceInfo: SourceInfo): (Option[LazyModule], () => Unit) = {
     (None, () => { bi <> bo })
   }