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