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