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