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