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