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