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