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