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