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