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