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