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