how to build multiple graphs on widget QCustomPlot

i want to build 5 graphs on my grid layout located on the scroll area.

Name of grid layout is "grap" But every time, when i run my code, i only see 1 graph on my widget. Down below i attached class of my graph. And i know that i will receive 5 equals graphs.

GraphBuilder.h

#ifndef GRAPHBUILDER_H
#define GRAPHBUILDER_H

#include "qcustomplot.h"

#include <QWidget>
#include <QObject>

class GraphBuilder : public QWidget
{
    Q_OBJECT
public:
    explicit GraphBuilder(QWidget* parent = nullptr);
    ~GraphBuilder();

    void build();

private:
    QCustomPlot* _customPlot = nullptr;
};

#endif // GRAPHBUILDER_H

GraphBuilder.cpp

#include "graphbuilder.h"

GraphBuilder::GraphBuilder(QWidget* parent)
    : QWidget(parent)
{
    _customPlot = new QCustomPlot(this);
}

GraphBuilder::~GraphBuilder()
{
    delete _customPlot;
}


void GraphBuilder::build()
{
    QVector<double> xData = {1, 2, 3, 4, 5};
    QVector<double> yData = {1, 4, 9, 16, 25};

    _customPlot->addGraph();
    _customPlot->graph()->setData(xData, yData);

    _customPlot->xAxis->setLabel("X");
    _customPlot->yAxis->setLabel("Y");

    _customPlot->xAxis->setRange(0, 6);
    _customPlot->yAxis->setRange(0, 30);

    _customPlot->replot();
}

MainWindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include "graphbuilder.h"

#include <QMainWindow>



QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();


private:

    void printGraph();

    Ui::MainWindow *ui;
    GraphBuilder* graph = nullptr;

};
#endif // MAINWINDOW_H

MainWindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);


    graph = new GraphBuilder();
    printGraph();
}

MainWindow::~MainWindow()
{
    delete ui;
    delete graph;
}


void MainWindow::printGraph()
{
    for (int i = 0; i < 5; i++)
    {
        ui->grap->addWidget(graph);
        graph->build();
    }
}

Photo->

graph show