One vertex per element, one color per generator, with an edge from x to x·s.
(5,8)(9,10)(11,18)(12,14)(13,23)(15,17)(16,19)(20,24)(21,22)(25,26)(27,31)(28,35)(29,37)(30,33)(32,34)(36,39)(38,40) involution — undirected(1,2)(3,5)(4,6)(7,8)(9,11,14,20)(10,16,12,22)(13,21,15,19)(17,24,23,18)(25,27,30,29)(26,31,33,37)(28,34,36,38)(32,35,40,39)(1,3)(2,5)(4,7)(6,8)(9,12,14,10)(11,18,20,24)(13,23,15,17)(16,19,22,21)(25,28,30,36)(26,32,33,40)(27,34,29,38)(31,39,37,35)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.