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