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