def payload_to_str_base(payload):
    """
    Converts a given payload to its str_base representation.
    A str_base payload is for example: "0xFF 0xFF 0xFF 0xFF".

    :param payload: The payload to be converted.
    :return: Returns the str_base representation of the payload.
    """
    result = ""
    for i in range(0, len(payload), 2):
        result += "0x" + payload[i] + payload[i + 1] + " "
    result = result[:len(result) - 1]
    return result