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