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)(25,26,30,34,29,33,36,40)(27,35,28,32,37,31,39,38)(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)(26,31)(28,30)(29,37)(32,40)(33,35)(34,38)(36,39)(1,2)(3,6)(4,5)(7,8)(9,12,14,13)(10,16,18,17)(11,20,21,22)(15,23,19,24)(25,26)(27,35)(28,38)(29,33)(30,40)(31,37)(32,39)(34,36)(2,5)(6,7)(9,13,14,12)(10,17,18,16)(11,20,21,22)(15,23,19,24)(25,28)(26,32)(27,36)(29,39)(30,37)(31,34)(33,38)(35,40)(1,3,4,8)(2,6,5,7)(10,18)(15,19)(16,17)(23,24)(27,37)(28,39)(31,35)(32,38)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.