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