urxvt can read its settings from ~/.Xdefaults
For example, my ~/.Xdefaults is
tc@box:~$ cat ~/.Xdefaults
Aterm*scrollBar: false
Aterm*transparent: false
Aterm*title: Terminal
Aterm*foreground: black
Aterm*background: aquamarine
Aterm*font: Terminus-bold-20
Aterm*cursorColor: green
Aterm*fading: 70
Aterm*shading: 50
Aterm*color12: DodgerBlue1
Aterm*saveLines: 1000
fltk*scheme: gtk+
Xft.dpi: 96.0
urxvt*background: aquamarine
urxvt*foreground: black
urxvt*font: Terminus-bold-20
urxvt*scrollBar: false
Assigning colors you can use ones found in /usr/local/share/X11/rgb.txt