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