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