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