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)(27,28)(29,33)(30,31)(32,35)(34,36)(37,40)(38,39)(1,2,5,6)(3,4,7,8)(9,10,13,12)(11,14,16,15)(17,19,21,18)(20,23,24,22)(26,31)(28,35)(33,39)(36,37)(2,6)(3,7)(9,10,13,12)(11,15,16,14)(25,27)(26,28)(29,34)(30,32)(31,35)(33,36)(37,39)(38,40)(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)(26,32)(27,31)(29,37)(30,35)(33,34)(36,38)(39,40)(1,4)(2,7)(3,6)(5,8)(9,12,13,10)(11,14,16,15)(25,29,30,38)(26,33,31,39)(27,34,32,40)(28,36,35,37)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.