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