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