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