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