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