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