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