Antergos comes with its own grub theme, but it only shows the Antergos logo by default. The icons for other OSs are included (check /boot/grub/themes/Antergos-Default/icons/), but they need some tweaks to be shown in the menu.
First, it's a wise idea to make a backup of an important file that is going to be modified:sudo cp /etc/grub.d/30_os-prober /etc/grub.d/backup-of-30_os-prober
Then open this file and modify it as follows (assuming you're using gedit as a text editor):sudo gedit /etc/grub.d/30_os-prober
Find the line:export TEXTDOMAINDIR="${datarootdir}/locale"
Add the line:declare -l CLASS
Find the line:BOOT="`echo ${OS} | cut -d ':' -f 4`"
Add the line:CLASS=$LABEL
Find all occurences of:--class gnu-linux
Replace with:--class ${CLASS} --class gnu-linux
Now check that the icons names in folder /boot/grub/themes/Antergos-Default/icons/ match the "--class" name of each "menuentry". To do this, open the file grub.cfg, but do not modify it:sudo gedit /boot/grub/grub.cfg
For example, if the entry for Ubuntu MATE has the class name "ubuntu1", then the icon for MATE, has to be named "ubuntu1.png".
Finish with a grub update:sudo grub-mkconfig -o /boot/grub/grub.cfg
reboot and enjoy your new Antergos menu 🙂