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