Diagrams rhymes with:
electrocardiograms, histograms, holograms, kilograms, logograms, milligrams, sonograms, telegrams, electrocardiograms, histograms, holograms, kilograms, logograms, mailgrams, mammograms, micrograms, milligrams, polygram's, program's, programs, programs', reprograms, sonograms, telegrams
Diagrams sounds like:
decrying, degrange, desiring, desormeaux, diagraming, dickering, disagreeing, disarming, discerning, discerns, dogearing