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