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