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