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