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