graphviz is maintained by Ivan Lazar Miljenovic. He can be contacted by email or on IRC under the nickname ivanm. He also follows the haskell@haskell.org and haskell-cafe@haskell.org mailing lists.
This website was written at the urgings of Eric Kow who felt that graphviz could use some better more comprehensive documentation. It was built using pandoc with extra advice and help from its author John MacFarlane.