Path (graph) shower utility

[Durumdara]

Hi !

I need to create a program that read eml file headers, analyze the 
receive tags and create a path database. I finished with this program 
section.

But I want to show a graphical summary about the paths.

This is (what I want to show) like a graph - show ways, stations, etc, 
and I want to show the strength of lines (how many of mails use this way).

Can anyone known about a freeware tool, software, or python module that 
can show graphs with best alignments ?

Please help me. Thanx for it:
dd