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