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