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