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