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)(11,17,13,15)(12,16,22,20)(19,24,21,23)(25,26,32,30)(27,36,35,31)(28,33,40,38)(29,34,39,37)(1,2)(3,5)(4,6)(7,8)(9,11,14,13)(10,15,18,17)(12,19,22,21)(16,23,20,24)(25,27)(26,31)(28,34)(29,33)(30,36)(32,35)(37,40)(38,39)(9,10)(11,15)(12,16)(13,17)(14,18)(19,23)(20,22)(21,24)(25,28)(26,33)(27,37)(29,36)(30,38)(31,39)(32,40)(34,35) involution — undirected(9,10)(11,15)(12,20)(13,17)(14,18)(16,22)(19,24)(21,23)(25,29,32,39)(26,34,30,37)(27,33,35,38)(28,36,40,31)(9,12,14,22)(10,16,18,20)(11,19,13,21)(15,23,17,24)(25,30,32,26)(27,36,35,31)(28,38,40,33)(29,34,39,37)(1,3,4,7)(2,5,6,8)(9,13,14,11)(10,17,18,15)(12,21,22,19)(16,24,20,23)(25,31,32,36)(26,35,30,27)(28,39,40,29)(33,34,38,37)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.