Try to stack like nodes

GraphNode.js

@@ -58,6 +58,11 @@ class GraphNode {
       if (this.groups.size && !intersects(this.groups, node.groups)) {
         node.addAffinity(this, d => d <= 2 ? -INF : 0);
       }
+
+      // Try to stack nodes with the same label
+      if (node.label == this.label) {
+        this.addAffinity(node, (d, v) => v[0] == 0 ? 200 : 500);
+      }
     }
 
     for (let to of this.links) {

Layout.js

@@ -61,6 +61,10 @@ class Layout {
       let nodes = this.nodesFromGraphNodes(subgraph);
       this.groups_.push(new LayoutGroup(null, this.nodesByPos_, nodes));
     }
+    for (let labelGroup of this.graph_.nodesByLabel.values()) {
+      let nodes = this.nodesFromGraphNodes(labelGroup);
+      this.groups_.push(new LayoutGroup(null, this.nodesByPos_, nodes));
+    }
   }
 
   resolveLinks() {