Every fingering that fits a hand
5323
moderate
532x
easy
5686
hard
xcb9
easy
What is true of it
Cdim is C, E♭ and G♭ — 1, b3 and b5 counted from C.
The easiest of the 4 fingerings below is 5323: 4 fingers, held at the 2nd fret.
None of them uses an open string, so this chord moves up the neck unchanged — the same shape 1 fret higher is the chord a semitone above.
Where its notes are on the neck
The brass dots are C, the root. Everything else is a chord tone with its degree printed in it.
With a different note underneath
Cdim/E♭
x323
Cdim/G♭
x686
An inversion is the same chord with a different note lowest. The name changes to a slash name because the bass is what a listener hears as the foundation.