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