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