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