One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,3)(5,6,9,12)(7,13,14,20)(8,16,18,11)(10,17,19,15)(21,22,25,28)(23,26,30,33)(24,27,31,34)(29,35,36,32)(5,7,9,14)(6,10,12,19)(8,17,18,15)(11,20,16,13)(21,23)(22,26)(24,29)(25,30)(27,32)(28,33)(31,36)(34,35)(21,24)(22,27)(23,29)(25,31)(26,32)(28,34)(30,36)(33,35) involution — undirected(1,3,4,2)(7,14)(10,19)(13,20)(15,17)(22,28)(24,31)(26,33)(29,36)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.