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