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