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