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