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