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