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