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