It displays to whatever front-end you're using like Jupyter, but there's no option to save it to a file, which is weird considering .draw() from ExtendedRoadRunner calls SBMLDiagram.draw() which draws to a temporary .png. So there's currently no option to mention the name of the file yourself.

Also I'm wondering if i want to contribute should i do it under https://github.com/sys-bio/libsbml-draw instead? I assume lookin at the history that's no longer really in use?