This one possible way to do this:
<Button.Triggers>
<EventTrigger RoutedEvent="Button.Click">
<BeginStoryboard>
<Storyboard>
<ColorAnimation
Storyboard.TargetName="myAnimatedBrush"
Storyboard.TargetProperty="Color"
From="Red" To="Blue" Duration="0:0:7" />
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Button.Triggers>
But let's say I have:
<Storyboard x:Name="name">
<ColorAnimation
Storyboard.TargetName="myAnimatedBrush"
Storyboard.TargetProperty="Color"
From="Red" To="Blue" Duration="0:0:7" />
</Storyboard>
and want to reuse it a few times.
<Button.Triggers>
<EventTrigger RoutedEvent="Button.Click">
<BeginStoryboard>
//
// <---> what whould I put here??
//
</BeginStoryboard>
</EventTrigger>
</Button.Triggers>
I'm only interested in a XAML, not c#.
Edit:
After I used suggestions from answers I got an error:
Attribute {StaticResource myStoryboard} value is out of range.