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