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