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