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