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