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