This is a sample app using vivagraph javascript library. You can find from basic implementations (like graph generation) to more elaborated stuffs (like add a link between two nodes in runtime) here. Take a look on this animation.
Ruby on Rails is used as back-end, so make sure to have it installed.
In your terminal, run:
bundle installto install rails gems;rake db:seedto populate the database;rails sto start the server.
It's done. Just access your localhost url.
Feel free to add new functionalities and make improvements. Just fork it and send a pull request.