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