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