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