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