One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,8,4,6,3,7)(9,10)(11,20,23,15)(12,24,26,17)(13,19)(14,18)(16,22,32,27)(21,29)(25,38,40,33)(28,30)(31,35)(34,36)(37,39)(2,6)(7,8)(9,11)(10,15)(12,21)(13,27)(14,23)(16,30)(17,29)(18,20)(19,32)(22,28)(24,34)(25,39)(26,36)(31,38)(33,37)(35,40) involution — undirected(1,3,4,5)(2,7,6,8)(9,11)(10,16)(12,21)(13,27)(14,23)(15,19)(17,31)(18,32)(20,30)(22,28)(24,37)(25,39)(26,36)(29,33)(34,38)(35,40)(2,6)(7,8)(9,12,14,26)(10,17,18,24)(11,21,23,36)(13,25,28,40)(15,29,20,34)(16,31,32,37)(19,33,30,38)(22,35,27,39)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.