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