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