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