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)(25,26,31,35)(27,29,37,32)(28,33,38,39)(30,40,36,34)(9,11,13,19)(10,14,16,17)(12,18,20,24)(15,21,22,23)(25,27)(26,32)(28,33)(29,35)(30,40)(31,37)(34,36)(38,39)(2,6)(7,8)(9,12,13,20)(10,15,16,22)(11,18,19,24)(14,21,17,23)(25,28)(26,33)(27,36)(29,34)(30,37)(31,38)(32,40)(35,39)(1,3,5,4)(2,7,6,8)(10,16)(14,17)(15,22)(21,23)(25,29,31,32)(26,27,35,37)(28,34,38,40)(30,33,36,39)(1,4,5,3)(2,8,6,7)(11,19)(14,17)(18,24)(21,23)(25,30)(26,34)(27,28)(29,39)(31,36)(32,33)(35,40)(37,38)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.