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