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