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)(11,21)(12,16)(13,20)(14,19)(15,18)(17,23)(22,24)(25,26)(27,31)(28,30)(29,32)(33,40)(34,37)(35,38)(36,39) involution — undirected(1,3,4,8)(2,5,6,7)(9,11,14,12)(10,16,19,21)(13,22,15,23)(17,18,24,20)(26,30)(27,33)(29,35)(31,39)(34,36)(37,40)(9,12,14,11)(10,17,19,24)(13,23,15,22)(16,20,21,18)(25,27)(26,31)(28,34)(29,36)(30,37)(32,39)(33,35)(38,40)(2,6)(5,7)(9,13,14,15)(10,18,19,20)(11,22,12,23)(16,24,21,17)(26,30)(27,34)(32,38)(33,36)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.