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