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