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