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