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