Proper modeling concepts are essential towards the effective design of XML based Data Warehouse (DW) system in presence of semi-structured multidimensional data. From the methodological point of view, such model should facilitate the representation of multidimensional XML data and the associated structures in order to perform OLAP in XML based DW. Thus a systematic transformation mechanism is essential to represent the conceptual level XML based DW schema in equivalent XSD at the logical level. This paper has proposed a rule based transformation mechanism for systematic transformation of a graph semantic based conceptual model for XML based DW (GXDW model) schema into the equivalent XML Schema Definitions (XSD). This is also capable to render a unified representation of GXDW model using XML based techniques to apprehend different logical schemas of DW like star, snowflake, and constellation etc. The expressive power of the proposed approach has been illustrated using suitable examples.