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