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