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