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