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