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