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