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