Depending on the number of units, Strata committee (SC) agenda and minutes may only have to be placed on a notice board if this has been voted for at some point – even if most owners are investors who rarely if ever pass the board.
In NSW and presumably all jurisdictions the SC does and can not make decisions to alter common property (CP) which a change of colours certainly is. Thus any work paid for by the OC which involves alteration of CP has by definition involved misappropriation of funds and legal action could be taken by the OC against whoever authorized payment. Happily for most SC members this is likely to be one individual who falsely advised the Strata Mgr. (SM) that the OC had approved the payment.
I don’t know if its available but my first recommendation for any OC hiring a Strata Mgr. would be to have a clause in the contract that it is the SM’s responsibility to sight and record evidence that any decisions involving SM action were decided at a properly convened meeting of the relevant body; otherwise my guess is that SM’s defence would be that when a decision is presented by the Secretary it is presumed that somewhere/sometime a proper meeting was held.