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