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