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