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