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