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