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