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