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