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