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