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