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