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