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