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