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