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)(11,21)(12,26)(13,17)(14,31)(15,20)(16,23)(18,29)(19,28)(22,32)(24,35)(25,34)(27,38)(30,37)(33,40)(36,39) involution — undirected(1,2)(3,6)(4,5)(7,8)(9,11,14,23,15,25,28,24)(10,16,19,21,20,35,31,34)(12,27,13,22,29,39,30,40)(17,36,26,32,37,38,18,33)(2,5)(6,7)(9,12,14,13,15,29,28,30)(10,17,19,26,20,37,31,18)(11,22,24,27,25,40,23,39)(16,32,34,36,35,33,21,38)(1,3,4,8)(2,6,5,7)(9,12,28,30,15,29,14,13)(10,17,31,18,20,37,19,26)(11,22,23,39,25,40,24,27)(16,32,21,38,35,33,34,36)(9,13,14,29,15,30,28,12)(10,18,19,17,20,26,31,37)(11,22,23,39,25,40,24,27)(16,33,21,36,35,32,34,38)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.