open template calandar_monthly_day
replace all with
(code changes highlighted in red)
<td>
<vb:if condition="$show['highlighttoday']">
<div class="events today">
<vb:else />
<div class="events">
</vb:if>
<vb:if condition="$show['weeklink']"><a class="weeklink" href="calendar.php?{vb:raw session.sessionurl}c={vb:raw calendarid}&week={vb:raw firstweek}&do=displayweek&month={vb:raw month}" title="{vb:rawphrase view_this_week_in_detail}"><vb:if condition="$stylevar['textdirection'] == 'rtl'">←<vb:else />→</vb:if></a></vb:if>
<a class="daynum" href="calendar.php?{vb:raw session.sessionurl}do=getinfo&day={vb:raw year}-{vb:raw month}-{vb:raw day}&c={vb:raw calendarid}"><vb:if condition="$day == 1">{vb:raw monthname} </vb:if>{vb:raw day}</a>
<vb:if condition="$show['eventlink'] OR $userevents OR $show['birthdaylink'] OR $userbdays">
<ol>
<vb:if condition="$show['eventlink']">
<li><a href="calendar.php?{vb:raw session.sessionurl}do=getinfo&day={vb:raw year}-{vb:raw month}-{vb:raw day}&c={vb:raw calendarid}" class="eventlinks" title="{vb:raw eventdesc}">{vb:rawphrase events}</a> ({vb:raw eventtotal})</li>
<vb:else />
<div class="eventlink">
{vb:raw userevents}
</div>
<vb:if condition="$show['birthdaylink']">
<li><a href="calendar.php?{vb:raw session.sessionurl}do=getinfo&day={vb:raw year}-{vb:raw month}-{vb:raw day}&c={vb:raw calendarid}" title="{vb:raw birthdaydesc}">{vb:rawphrase x_birthdays, {vb:raw bdaycount}}</a></li>
<vb:else />
{vb:raw userbdays}
</vb:if>
</vb:if>
</ol>
</vb:if>
</div>
</td>
Add the following to additional.css
.eventlink a, a.eventlinks {color:#FF0000;}
.eventlink a:hover, a.eventlinks:hover {color:#0000ff;}
.eventlink a:active, a.eventlinks:active {color:#cc00ff;}
change color values to what you want.
Refer to image below for results. Red links are events.