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