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