Hi Gangireddy,
there is no standard customizing to change color for your requirement as said Bruce Li,
what you have to do is go to that class cl_chtmlb_calendar_month method render_calendar_body
there is a statement for background color.
IF ME->REFERENCE_DATE+4(2) <> IV_DATE+4(2) AND
ME->PRINT_MODE EQ 'FALSE'.
* LV_BACKGROUND = '#F9F9F9'.
* Commented by STEFANOVST, causing issue in IE7
* @todo: Maybe in general, colors should be defined in CSS
ELSE.
IF ME->PRINT_MODE EQ 'FALSE'.
LV_BACKGROUND = cl_thtmlb_util=>escape_xss_xml_html( ME->CALENDARBACKGROUND ).
ELSE.
LV_BACKGROUND = 'FFFFFF'.
ENDIF.
ENDIF.
just change the color code in run time you will get colors..
i have checked in my system this will work like this.
what you have to do is create implicit enhancement for that method and try to implement code according to your requirement.
try to explore this link might be helpful to you. these is related to factory calendar based on holidays she has populated color but in your Scenario you have to populate color based on ur condition.
Display Factory/Holiday calendar in date field in WEB UI
Regards,
Srinivas.