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