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