'pre-' originates from Latin, specifically the prefix 'prae' where 'prae-' meant 'before', combined with 'colored', which ultimately comes from Latin 'color' via Old French 'colour'.

'pre-colored' is a Modern English compound formed by prefixing 'pre-' to the past-participial/adjectival form 'colored' (from Middle English 'colour' < Old French 'colour' < Latin 'color').

Initially, it meant 'colored beforehand', and this basic sense has been retained in modern usage as 'already colored/ dyed prior to use'.