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