下記の場合、背景色は赤で表示される

                        <DataGridTemplateColumn>
                            <DataGridTemplateColumn.CellStyle>
                                <Style TargetType="{x:Type DataGridCell}">
                                    <Style.Triggers>
                                        <DataTrigger Binding="{Binding ID}" Value= "1">
                                            <Setter Property="Background" Value="Red"/>
                                        </DataTrigger>
                                        <DataTrigger Binding="{Binding ID}" Value= "2">
                                            <Setter Property="Background" Value="Orange"/>
                                        </DataTrigger>
                                        <DataTrigger Binding="{Binding ID}" Value= "3">
                                            <Setter Property="Background" Value="Yellow"/>
                                        </DataTrigger>
                                        <DataTrigger Binding="{Binding ID}" Value= "4">
                                            <Setter Property="Background" Value="Gray"/>
                                        </DataTrigger>
                                    </Style.Triggers>
                                    <Setter Property="HorizontalAlignment" Value="Center" />
                                </Style>
                            </DataGridTemplateColumn.CellStyle>
                            <DataGridTemplateColumn.CellTemplate>
                                <DataTemplate>
                                    <StackPanel>
                                        <TextBlock Text="1" Padding="1" TextAlignment="Center"/>
                                    </StackPanel>
                                </DataTemplate>
                            </DataGridTemplateColumn.CellTemplate>
                        </DataGridTemplateColumn>