One vertex per element, one color per generator, with an edge from x to x·s.
(2,3)(5,6)(7,10)(8,11)(9,13)(12,17)(14,18)(15,20)(16,19)(21,22)(23,31)(24,27)(25,30)(26,29)(28,34)(32,35)(33,36) involution — undirected(1,2,4,3)(5,7,9,15)(6,10,13,20)(8,16,17,14)(11,19,12,18)(22,27)(23,32)(25,26)(28,31)(33,34)(35,36)(6,11)(8,17)(10,18)(12,13)(14,16)(19,20)(21,23,24,33)(22,28,27,35)(25,32,26,34)(29,36,30,31)(1,3,4,2)(22,27)(28,35)(29,30)(31,36)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.