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