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