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