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