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