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