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