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