I found the book at the library. Seems I was off a few. The longest known word that can be K-graphed is diaminopropyltetramethylenediamine (34 letters), shown below.

Of course, probably nobody knows what diaminopropyltetramethylenediamine is. However, this makes my k-graph of antidisestablishmentarianism somewhat irrelevant to me. Anyway, K-graphs are so named because the letters can connect in the ways a king moves on a chessboard. Anyway, I'm going to Borders tomorrow to see if I can find it (I probably won't be able to, which is why I went to the library and loaned it.) Anyway, I'll keep working on K-graphing stuff, it seems to be fun.