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