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