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