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