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