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)(27,33)(28,31)(29,32)(30,36)(34,38)(35,40)(37,39)(2,5)(6,7)(11,19)(15,23)(18,24)(20,21)(25,27,34,35,28,36,29,37)(26,30,38,39,31,33,32,40)(9,11,13,19)(10,15,16,23)(12,21,14,20)(17,24,22,18)(27,35)(29,34)(30,39)(32,38)(33,40)(36,37)(1,3,4,8)(2,6,5,7)(10,16)(15,23)(17,22)(18,24)(26,31)(30,33)(32,38)(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.