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