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