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