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