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