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