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