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