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