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)(25,26,30,35,31,36,29,32)(27,33,38,40,37,28,34,39)(1,3,4,7)(2,5,6,8)(11,18)(12,21)(14,17)(15,20)(26,32)(27,37)(28,39)(29,30)(33,40)(35,36)(2,6)(5,8)(9,11)(10,14)(12,19)(13,18)(15,22)(16,17)(20,23)(21,24)(25,27)(26,33)(28,36)(29,34)(30,38)(31,37)(32,39)(35,40) involution — undirected(11,18)(14,17)(19,24)(22,23)(25,28,29,40,31,33,30,39)(26,34,32,37,36,38,35,27)(9,12,13,21)(10,15,16,20)(11,19,18,24)(14,22,17,23)(25,29,31,30)(26,35,36,32)(27,38,37,34)(28,40,33,39)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.