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