You may find that gnuplot's for loops are useful in this case, if you adjust your filenames or graph titles appropriately.
e.g.
filenames = "first second third fourth fifth"
plot for [file in filenames] file."dat" using 1:2 with lines
and
filename(n) = sprintf("file_%d", n)
plot for [i=1:10] filename(i) using 1:2 with lines