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