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