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