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