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