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