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