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