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