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