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