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