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