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