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