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