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