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