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