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)(28,32)(31,37)(33,38)(34,35)(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)(26,31)(30,37)(33,39)(38,40)(1,4,5,2)(3,7,8,6)(9,11)(10,14)(12,19)(13,18)(15,23)(16,17)(20,24)(21,22)(25,26,32,37,29,31,28,30)(27,33,34,40,36,39,35,38)(3,8)(6,7)(11,18)(14,17)(19,21)(23,24)(25,27)(26,33)(28,35)(29,36)(30,38)(31,39)(32,34)(37,40) involution — undirected(9,12,13,22)(10,15,16,20)(11,19,18,21)(14,23,17,24)(25,28,29,32)(26,30,31,37)(27,34,36,35)(33,40,39,38)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.