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