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