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