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