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