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)(11,19,21,15)(12,18,14,16)(20,24,22,23)(25,26,29,31)(27,35,38,40)(28,34,30,33)(32,36,39,37)(1,3,5,4)(2,6,8,7)(9,11)(10,15)(12,22)(13,21)(14,20)(16,23)(17,19)(18,24)(26,31)(27,36)(28,30)(32,35)(37,38)(39,40)(10,16)(12,14)(15,23)(17,18)(19,24)(20,22)(25,27,29,38)(26,32,31,39)(28,36,30,37)(33,40,34,35)(1,4,5,3)(2,7,8,6)(9,12,13,14)(10,16,17,18)(11,20,21,22)(15,24,19,23)(25,28,29,30)(26,33,31,34)(27,37,38,36)(32,35,39,40)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.