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