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