<Style x:Key="ArrowToggleStyle" TargetType="ToggleButton">
    <Setter Property="Background" Value="Gray"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="ToggleButton">
                <Border Background="{TemplateBinding Background}">
                    <Grid>
                        <Image x:Name="leftArrowImg" Source="/Graphics/arrow_left24.png" Width="24" Height="24"  HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                        <Image x:Name="rightArrowImg" Source="/Graphics/arrow_right24.png" Width="24" Height="24"  HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                        <ContentPresenter x:Name="content1" Content="not selected" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                        <ContentPresenter x:Name="content2" Content="SELECTED" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                    </Grid>
                </Border>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsChecked" Value="True">
                        <Setter Property="Background" Value="DimGray"/>
                        <Setter TargetName="leftArrowImg" Property="Visibility" Value="Hidden"/>
                        <Setter TargetName="rightArrowImg" Property="Visibility" Value="Visible"/>
                        <Setter TargetName="content1" Property="Visibility" Value="Hidden"/>
                        <Setter TargetName="content2" Property="Visibility" Value="Visible"/>
                    </Trigger>
                    <Trigger Property="IsChecked" Value="False">
                        <Setter TargetName="leftArrowImg" Property="Visibility" Value="Visible"/>
                        <Setter TargetName="rightArrowImg" Property="Visibility" Value="Hidden"/>
                        <Setter TargetName="content1" Property="Visibility" Value="Visible"/>
                        <Setter TargetName="content2" Property="Visibility" Value="Hidden"/>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

WPF ToggleButton Style