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