When I look at most of the websites people demonstrate their git workflow in pictorial fashion.
I would like to know which tool is used for the same ?
For example https://wiki.phpbb.com/images/c/c8/Phpbb-git-workflow-small.png
and http://nvie.com/posts/a-successful-git-branching-model/
I am implementing git for the enterprise and would like to show a similar diagrammatic representation (as show in example), so I was wondering if there was a tool which will help me build it
I asked Vincent Driessen about the diagram creator program he used for his blog post http://nvie.com/posts/a-successful-git-branching-model/ and he mentioned that he used Apple Keynote.
Personally I am playing around with draw.io for diagram creation and I'm liking it so far. It is free thus far and is pretty simple to use.
If your question is about creating diagrams specific to your git repository history then I would suggest using GitFlowChart. Vincent has an example showing GitFlowChart here.