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