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