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)(11,15)(12,17)(13,16)(14,19)(18,25)(20,31)(21,29)(22,30)(23,28)(24,33)(26,32)(27,35)(34,38)(36,40)(37,39) involution — undirected(1,3,4,8)(2,5,6,7)(9,11)(10,15)(12,24)(13,20)(14,23)(16,31)(17,33)(18,30)(19,28)(21,26)(22,25)(27,36)(29,32)(34,39)(35,40)(37,38)(2,6)(3,8)(10,16,19,18)(11,20,23,22)(15,28)(17,32,35,34)(21,36,37,24)(29,39)(30,31)(33,40)(2,6)(5,7) involution — undirected(9,12,25,38,14,27,13,26)(10,17,18,34,19,35,16,32)(11,21,20,36,23,37,22,24)(15,29,31,40,28,39,30,33)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.