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