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