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