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