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