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