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