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