Not a perl answer.

But it sounds like you want something similar to what McCabe software has for java.

The above page doesn't mention perl support, but here perl is mentioned, kind of obscurely, so maybe they they have something if you want to ask.

I actually set up a demo with them once (for java), and it was really cool.

Horribly expensive though. No pricing info on their web page, first they give the demo then the shocking numbers. But that was over five years ago, maybe things have changed.

Since you asked about visualizing perl code, I'm guessing you inherited some code and want to get a handle or broad overview on it. I asked for and got some help on a (I think) related problem here at grepping out global vars?.