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