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