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