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