Please do not hijack this Java API question with a different topic (UI questions).
I'll answer your questions here but if you want to continue the discussion please open a new question topic.
If you want to view Graphs in Kibana install the x-pack plugin and here is an example of how to configure the UI.
That would be done outside of elasticsearch/kibana currently. We are working on an export-to-GraphML feature which would allow you to use tools like Gephi which offer various Graph algos e.g. shortest-path, centrality measures, community detection etc wrapped up in a UI. If you just want to write code that does graph analysis consider using tools like Python's NetworkX library - here is an example calling the Graph API and performing betweenness centrality measures using networkX.
If you want to discuss any of the above further please open a new topic so we can keep this one focused on the Java API.