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