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)(26,31)(29,32)(33,39)(37,40)(1,2)(3,7)(4,5)(6,8)(9,11,14,19)(10,13,16,17)(12,18,20,21)(15,22,23,24)(2,5)(6,7)(12,20)(15,23)(18,21)(22,24)(25,26)(27,32)(28,33)(29,34)(30,31)(35,40)(36,37)(38,39) involution — undirected(2,5)(6,7)(9,11)(10,13)(12,21)(14,19)(15,24)(16,17)(18,20)(22,23)(25,27,30,34)(26,32,31,29)(28,36,38,35)(33,37,39,40)(1,2)(3,6)(4,5)(7,8)(9,12,14,20)(10,15,16,23)(11,18,19,21)(13,22,17,24)(25,28,30,38)(26,33,31,39)(27,35,34,36)(29,37,32,40)(1,3)(2,6)(4,8)(5,7)(9,13)(10,11)(12,22)(14,17)(15,18)(16,19)(20,24)(21,23)(25,29,30,32)(26,34,31,27)(28,37,38,40)(33,36,39,35)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.