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