Recently, there were some emails on the Linked Data community distribution list about the tools used to generate the LOD cloud diagram. One of the replies discussed a very simple approach - using GraphML and the
yEd editor .
yed's "organic" layout, a reasonable representation can be achieved which is then manually brought in shape with yed (positioning) and XML (font adjustment). In yed, we augment it with a legend and text and then export it into the graphic format of choice."
Given that yEd is free, I decided to investigate a similar approach for diagramming OWL ontologies. I started with creating some simple XSL transforms to go from RDF/XML to GraphML. The XSLTs are found on GitHub