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