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