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