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