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