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