Try out graphalchemist

[macbre]

http://graphalchemist.github.io/Alchemy/#/examples

Clustering nodes will have a major effect on layout and color. This is one of Alchemy's most powerful off the shelf features. To cluster nodes, simply set cluster to true. Alchemy.js will expect a 'cluster' key for each node in the provided GraphJSON whose value is an integer.

http://jsongraphformat.info/