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