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