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