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