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