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