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