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