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