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