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