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