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