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