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