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