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)(11,15)(12,13)(14,16)(19,23)(22,24)(25,26,30,29)(27,31,35,34)(28,36,38,32)(33,40,37,39)(2,3)(4,8)(9,10,12,13)(11,15,16,14)(17,18,21,20)(19,22,23,24)(26,29)(31,34)(32,36)(39,40)(2,3)(6,7)(10,13)(14,15)(17,18,21,20)(19,22,23,24)(25,27,30,35)(26,31,29,34)(28,37,38,33)(32,40,36,39)(1,3,5,2)(4,7,8,6)(9,10)(11,14)(12,13)(15,16)(17,19)(18,22)(20,24)(21,23)(25,28,30,38)(26,32,29,36)(27,33,35,37)(31,39,34,40)(1,4,5,8)(2,6,3,7)(9,11,12,16)(10,14,13,15)(17,20,21,18)(19,24,23,22)(25,29,30,26)(27,34,35,31)(28,36,38,32)(33,40,37,39)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.