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