There are two problems here, although I can really only speak for texlive/Mac OS X. LuaTeX restricts loading modules to those that can be found with the kpathsea libray. So you might have luck putting the libraries in your document folder or perhaps using an absolute path, but I think require() won't be happy with it.
The next might not apply to windows. On my system, Mac OS X, you can't load arbitrary modules during runtime, because some symbols are stripped from the LuaTeX executable and some external libraries require them in the binary. See for example a bug report on the LuaTeX tracker.
requireexpects a string. Have you triedrequire("luagraph")? – Bruno Le Floch Aug 2 '12 at 9:57