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