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