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