정성훈.해미님이 주신 답변을 응용하여 해결을 했습니다.

void __fastcall T_MAIN::DBGrid3DrawColumnCell(TObject *Sender,
      const TRect &Rect, int DataCol, TColumn *Column,
      TGridDrawState State)
{
static int row_index;
        DBGrid3->Canvas->Font->Color = Chart1->Series[row_index]->SeriesColor; //색깔 지정
        DBGrid3->Canvas->FillRect(Rect);
        DBGrid3->Canvas->TextOut(Rect.Left+1, Rect.Top+3, Column->Field->AsString);
        if(++row_index>(selectcount-1))                                                                      //행 갯수
                row_index=0;
      //selectcount = ADOQuery10->RecordCount;
}

기쁩니다.^^
감사합니다.