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