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