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