Sorry but the range of speeds for ICAO is 121/140 for C and 141/165 for D.
In my FCTM page 5.4 "the 737-800 is classified as a Category "C" or "D" airplane, depending upon maximum landing weight, for straight-in approaches"
And I am sure my 737-800 has a 141 Vref for flaps 40 even until 1000kg below MLM
No idea about the graph your takinŽabout (page?)
Thank u anyway
Javier