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