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