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