There is not setting to control if the maps in vote are random or alphabetically sorted.
You need to remove these lines from the plugin, recompile and install it on your server:
Code:
File: addons\amxmodx\scripting\galileo.sma
7473: // Alphabetize the maps
7474: SortCustomSynced2D( g_votingMapNames, g_votingMapInfos, g_totalVoteOptions );
__________________