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