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