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