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