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