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