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