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