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