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