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