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