Hi there,
You would need to replace the logo with an inline SVG:
add_filter( 'generate_logo_output', function() {
return sprintf( // WPCS: XSS ok, sanitization ok.
'<div class="site-logo">
<a href="%1$s" title="%2$s" rel="home">
YOUR SVG HTML HERE
</a>
</div>',
esc_url( apply_filters( 'generate_logo_href' , home_url( '/' ) ) ),
esc_attr( apply_filters( 'generate_logo_title', get_bloginfo( 'name', 'display' ) ) )
);
} );
Then you can target the SVG element with CSS to color it.