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