Many tools can generate dependency graphs of classes or (sometimes) larger modules. Is there an advantage in starting your Mikado graph with an auto-generated graph like this, perhaps as an overlay or as a guide map?
The purpose of the Mikado Graph is to represent the dependencies of just the things you need to change. This is usually not the same as the dependencies in the code base, although the dependencies in the code base will of course influence the order in which you need to do things.
So the answer is no, it's not a good starting point for a Mikado Graph, but it is a good source of information about your system. :-)