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