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