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