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