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