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)(19,24,22,23)(26,31)(27,33)(34,38)(35,40)(1,2,5,6)(3,7,8,4)(10,15)(11,18)(12,21)(23,24)(25,26,30,31)(27,32,33,28)(29,34,37,38)(35,39,40,36)(2,6)(4,7)(10,15)(13,16)(17,20)(23,24)(29,37)(34,38)(35,40)(36,39) involution — undirected(1,3,5,8)(2,7,6,4)(9,11,14,18)(10,16,15,13)(12,22,21,19)(17,23,20,24)(25,27)(26,32)(28,31)(29,35)(30,33)(34,39)(36,38)(37,40)(1,3)(2,4)(5,8)(6,7)(9,12,14,21)(10,17,15,20)(11,19,18,22)(13,23,16,24)(25,28,30,32)(26,33,31,27)(29,36,37,39)(34,40,38,35)(1,4)(2,3)(5,7)(6,8)(9,13,14,16)(10,18,15,11)(12,23,21,24)(17,22,20,19)(25,29)(26,34)(27,35)(28,36)(30,37)(31,38)(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.