The mincrosssings is a GNU GPL free sugiyama barycenter layout algorithm in C with tools and documentation available, ready to create your own GPL free graph layout program.

https://github.com/mfms-ncsu/Crossing-Minimization

and https://people.engr.ncsu.edu/mfms/

and a local backup is here in mincrossings.tar.gz

documentation to see the c source is here in these doxygen pages

In fact only need to add a parser and drawing part and few more graph routines to it to make a tool.

Other graph software from matthias stallman is here in stallman-software.tar.gz
and better explained what it is about here

And this is used for chip design with such kind of graph data:
chip