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