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