Text is not always the best way to represent anything and everything to do with a computer programs. Pictures and images are easier to assimilate than text. The ability to show a particular thing graphically can aid a great deal in comprehending what that thing really represents. They also allow relations to be expressed between elements without labeling the elements. A friend of mine used this to his advantage when trying to remember important dates in computer history.
Spreadsheets are also a wonderfully simple graphical representation of computational models.
Note that Marcel Grunauer has released some modules on CPAN to graph various other structures. This is the constructor. It accepts several attributes. Setting this to zero produces undirected graphs, which are layed out differently. Another attribute 'rankdir' controls the direction the nodes are linked together.