According to the Answer of the Question "Symbol color of SVG in mapfile" on gis stackexchange:

There is this SVG symbol from the MapServer GitHub repository: https://github.com/MapServer/MapServer/blob/main/msautotest/misc/data/Road_Works.svg

It is included in this symbolset https://github.com/MapServer/MapServer/blob/main/msautotest/renderers/symbolset

The symbol is used in two mapfiles in the msautotest set

1. https://github.com/MapServer/MapServer/blob/main/msautotest/renderers/point_svg.map
2. https://github.com/MapServer/MapServer/blob/main/msautotest/renderers/line_marker_svg.map

The latter mapfile includes "color"

 style
            symbol "svgicon"
            gap -20
            size 5
            initialgap 0
            color 0 0 0
  end

However, in the expected output the Road Works symbol is not black. https://github.com/MapServer/MapServer/blob/main/msautotest/renderers/expected/line_marker_svg.cairo.png