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