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