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