If you are not familiar with Graphviz, it is an excellent open source graph visualization tool that utilizes a “dot” language as specification for the generation of graphs. These “dot” files can be created manually or programmatically, thereby making Graphviz a very powerful tool. This article provides a good introduction on Graphviz and how to get started with using it. The author starts at the very beginning by explaining how to install the software and ends up with walking you through creating a few somewhat advanced “dot” file specified graphs.

An Introduction to Graphviz (robrhnehart.com)