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