I'm not a huge authority on the 1st Crusade, but in terms of clothing and uniform, both sides tended to adopt very similar clothing. Even excluding Saladin's Frankish mercenary contingent or the native Christians who fought for the Franks, both sides began using similar equipment and dress,
for colours, clothing generally consisted of a single coloured one-piece tunic.
The Knights who took up the cross would go with a simple cloak worn over their usual clothing.
Having said all this, it is probably highly open to interpretation as battle and campaign gear varied widely, and the illustrations produced by chroniclers and artists is rarely representative of the majority, reality or produced accurately.