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