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