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