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