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