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