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