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