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