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