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