great responses above. i'm not very theory based, but here's how i improved at triads...
if you're good at memorizing patterns, that will help you be able to quickly identify notes.
i found it's very useful to memorize the root note positions.
you can also play a triad, name the triad, and then determine the root note of that triad.
for example, if you play the A major triad, that's 6-5-5 on the (3rd, 2nd, and 1st strings respectively).
the root note is on the 1st string (A). then go through the fretboard to identify all triads in the key of A.
what also helps me is playing a 3 chord sequence using only triads.
that helps me get more used to playing triads in the context of a chord sequence, rather than only memorizing the triads where they are on the fretboard.
what you'll probably find is that the same chord sequence can be played without moving your fingers very far from the frets.
once you find one set of chords, you can try to find the same sequence on a different part of the fretboard.
for a 3rd exercise, you can also try playing the relative minor of the key.
this is a lot more challenging. bring up the circle of fifths if you're having trouble with this.
this will help you play both major and minor keys, then find the relative major/minor for that key.
really helps when you can play the relative minor for a major key.
anyway, just my two cents. hope it helps :)