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