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