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