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