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