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