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