This isn't really what you're asking for, but since no-one else has mentioned it, the call hierarchy feature built into most IDEs gets about 50% of the way ther

This isn't really what you're asking for, but since no-one else has mentioned it, the call hierarchy feature built into most IDEs gets about 50% of the way there. The obvious limitations are that this usually only works for one function at a time, and shows a tree not a graph.