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