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