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