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