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