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