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