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