C++ code visualization

Why not just do it manually, it is a great learning experience when starting to work with a large code base. I usually just look at what class inherits from what, and what class contain what instances, references or pointers to other classes. Have a piece of paper next to you and get drawing...

A good UML tool should do the trick.

Here is a list of generic UMl tools: http://en.wikipedia.org/wiki/List_of_UML_tools

There are lots out there, all with varying feature sets. Try playing with a few to see if you get the output you desire. If they free ones fail you, you might have to shell out for a good commercial grade UML tool

Instead of going into the full Class Designer tool, just use the "Class View" or the "Object Browser" in Visual Studio - they present fully collapsible class heirarchies.