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