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