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