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