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)(11,17,18,13)(12,16,20,23)(19,24,21,22)(25,26,31,28)(27,32,29,33)(30,36,38,34)(35,40,37,39)(2,6)(3,7)(10,15)(11,18)(12,20)(22,24)(25,27,31,29)(26,32,28,33)(30,35,38,37)(34,39,36,40)(1,3)(2,4)(5,7)(6,8)(11,18)(12,20)(13,17)(16,23)(26,28)(27,29)(30,38)(39,40) involution — undirected(1,4)(2,3)(5,8)(6,7)(9,11)(10,13)(12,21)(14,18)(15,17)(16,24)(19,20)(22,23)(25,28,31,26)(27,32,29,33)(30,36,38,34)(35,39,37,40)(9,12)(10,16)(11,19)(13,22)(14,20)(15,23)(17,24)(18,21)(25,29,31,27)(26,33,28,32)(30,37,38,35)(34,40,36,39)(9,13)(10,11)(12,22)(14,17)(15,18)(16,19)(20,24)(21,23)(25,30)(26,34)(27,35)(28,36)(29,37)(31,38)(32,39)(33,40) 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.