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