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