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)(9,10)(13,14)(15,18)(16,20)(17,19)(21,22)(23,27)(24,29)(25,28)(26,30)(31,36)(32,34)(33,35) involution — undirected(6,10)(11,12)(13,15,17,16)(14,18,19,20)(21,23)(22,27)(24,32)(25,33)(26,31)(28,35)(29,34)(30,36)(5,7,9,8)(6,11,10,12)(13,16,17,15)(14,18,19,20)(22,28)(23,31)(24,26)(27,34)(32,33)(35,36)(2,4)(5,8,9,7)(6,12,10,11)(21,24,25,26)(22,29,28,30)(23,32,33,31)(27,34,35,36)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.