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)(19,23)(22,24)(25,26,30,31)(27,32,35,38)(28,37,39,33)(29,34,40,36)(1,3)(2,6)(4,7)(5,8)(9,10,13,14)(11,12,15,16)(18,21)(22,24)(26,31)(27,35)(33,37)(34,36)(2,7)(3,8)(10,14)(11,15)(17,18,20,21)(19,22,23,24)(25,27)(26,32)(28,36)(29,37)(30,35)(31,38)(33,40)(34,39)(1,3)(2,4)(5,8)(6,7)(9,11)(10,12)(13,15)(14,16)(17,19,20,23)(18,22,21,24)(25,28,30,39)(26,33,31,37)(27,36,35,34)(29,32,40,38)(1,4)(2,3)(5,6)(7,8)(9,12)(10,11)(13,16)(14,15)(25,29,30,40)(26,34,31,36)(27,33,35,37)(28,38,39,32)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.