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)(11,13)(12,14)(15,16)(18,21)(22,23)(25,26)(27,30)(28,31)(29,33)(32,36)(34,37)(35,39)(38,40)(1,3,4,8)(2,5,6,7)(9,11,12,15)(10,13,14,16)(17,18,20,21)(19,23,24,22)(10,14)(13,16)(18,21)(22,23)(25,27,29,35)(26,30,33,39)(28,34,36,40)(31,37,32,38)(3,8)(5,7)(17,19,20,24)(18,22,21,23)(26,31)(28,36)(30,37)(32,33)(34,40)(38,39)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.