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