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