Hi There
I will help you to use svg+gml+xsl+xslt to draw a same one.
i will do all following :
1. gml = Geography Markup Language xml
2. there are defined value between two rectangles, the line color is mapped to the value.
for example, higher value using deeper color.
3. each rectangle is a node
4. there one to many lines between two nodes(rectangle)
5. use gml:PolygonPropertyType, gml:CurvePropertyType, gml:AbstractFeatureType .. etc