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