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