Guitar and piano have the distinction of being two instruments in concert pitch, meaning that all their notes, scales, and chords are constructed the same. No transposing, or changing of keys, needs to be done to ensure the two are in pitch together. The difference in chordal layout between the two is that guitars lay their notes out vertically due to the arrangement of the strings, and piano keys make chords laid out horizontally.
Finger the guitar chord and any variation of it. Make note of all the notes that are being played.
Write down the notes of the chord if needed. At the piano, decide on the octave to be played.
Looking back at the guitar notes, find the same notes on the piano. The letter name of the chord, or the root, should be the first one played. Construct the order of notes on the piano as they would be in order on guitar, from lowest to highest. Find the desired hand positioning and fingers for each note.