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