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)(27,34)(28,38)(29,33)(30,32)(31,37)(35,40)(36,39)(2,5)(6,7)(9,11)(10,15)(12,18)(13,20)(14,19)(16,23)(17,22)(21,24)(25,27,29,37)(26,31,33,34)(28,36,30,35)(32,39,38,40)(9,12,13,10,14,16,21,17)(11,18,20,15,19,23,24,22)(27,35)(28,30)(31,39)(32,38)(34,40)(36,37)(1,3,4,8)(2,6,5,7)(11,19)(15,22)(18,23)(20,24)(25,28,29,30)(26,32,33,38)(27,36,37,35)(31,39,34,40)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.