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