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