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