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