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