FWIW, I found the english version of the Westin shuttle service map,
http://www.westin-osaka.co.jp/img/map/map_a4e.pdf
the Japanese version (nice picture of the big shuttle to look out for),
http://www.westin-osaka.co.jp/access/shuttle.html
the Osaka Station map to the shuttle (only the Japanese version seems to be available), red line for path to the shuttle pickup point, blue line for path to Westin on-foot.
http://www.westin-osaka.co.jp/access/stationmap2.html