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