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