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)(11,17)(12,20)(13,15)(14,18)(16,21)(19,22)(23,24)(25,26,29,34,30,33,28,31)(27,35,37,39,36,32,38,40)(2,5)(6,7)(9,11)(10,14)(12,19)(13,18)(15,17)(16,22)(20,23)(21,24)(26,31)(27,36)(28,29)(32,40)(33,34)(35,39) involution — undirected(1,3,4,8)(2,6,5,7)(10,15)(11,18)(16,20)(19,24)(25,27)(26,32)(28,38)(29,37)(30,36)(31,39)(33,35)(34,40)(11,18)(14,17)(19,24)(22,23)(25,28,30,29)(26,31,33,34)(27,37,36,38)(32,40,35,39)(9,12,13,21)(10,16,15,20)(11,19,18,24)(14,22,17,23)(26,33)(27,36)(31,34)(37,38)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.