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