When I need to easilly build a graph and draw it using graphviz, such as the one shown below, which shows subuser's repository layout, I use the myopic graph editor from the text graph ecosystem (rendered with graphviz ). Text graph files are designed specifically to not only check into git well, but to show nice, easy to understand, diffs.
Rabbit hole warning!
Here is a video showing the current state of the text graph ecosystem.
You can get the current text graph ecosystem with:
git clone http://git.hobbs.cz/clone/tg
I'm currently working on a manual.
The hotkeys for the myopic graph editor can be found here.
Text graph comes with a money back gauarantee!