How to set color of arrows?

Dear all,
I’m a new user of GMT and have a problem with converting the gmt codes from old version(4.x.x) to newer version of 5.4.4.
The older version draws wind-arrows in grey color while the newer in red color. We don’t know how to turn it back to grey.
Looking closly at the codes I see the older version has some commands like:
g_vector_txt="-G0/26/153"
g_vector_R_pijl_fill="-G133/138/132"
s_vector_R_pijl="-Svt0.015c/0.09c/0.08c"
All these kinds of commands seem not allowed any more. So I have no idea how to set the color.
Can anyone give me some hint? Any suggestion is welcome.
Thanks a lot!

Xueli

s_vector_R_pijl="-Svt0.015c/0.09c/0.08c"

Nope, GMT5 has stopped development some 4 or more years ago. New version is GMT6, where old syntax for arrows has been reestablished. But certainly it does not paint an arrow in red if it was not told to do so.