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