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