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