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