Makefile Graphs
If you have graph-easy (often in the package perl-graph-easy or similar), you can make a graph from the makefile with make2graph (the package is often called makefile2graph).
Start with the command to 'make all targets' (-B), and 'do a dummy run' (-n) with debug into (-d):
1make -Bnd
2make -Bnd | make2graph
3make -Bnd | make2graph | graph-easy --boxart