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