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