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