You can put colors into the grub.conf like this....
Code:
color black/black black/white
title *=*=*=*=*=*=*=*=*=*=*=*=* CDROM BOOT MENU *=*=*=*=*=*=*=*=*=*=*=*=*=*
default=0
timeout=15
title Fedora Core
root (hd1,1)
kernel /boot/vmlinuz-2.6.13-1.1532_FC4 ro root=LABEL=/ rhgb quiet
initrd /boot/initrd-2.6.13-1.1532_FC4.img
title PCLinuxOS
root (hd0,0)
kernel /boot/vmlinuz ro root=/dev/hda1
initrd /boot/initrd.img
title Berry
root (hd0,4)
kernel /boot/vmlinuz ro root=/dev/hda5
initrd /boot/initrd.gz
Edit: You may also prefer to leave the splash image in the grub.conf and edit it with the Gimp. Do a bucket fill with black color.