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