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