For the coloured guard infantry standards: the central circle was white; the large white sections were the same redish colour shown above, the small redish and white 'X' were all white. The regiments were differentiated only by the colour of the poles: Preobrazhensky : white standard coffee brown, coloured standards pail yellow; S: all poles were black. Cords were silver for all.

In 1805 (from 21.iii.1802), each guard regiment carried one white (carried by the 1st battalion) and five coloured standards, two per battalion. Same M. 1800 white and coloured standards.

From Mark Conrad's translation, Vol. 9:

"In 1800, when the Life-Guards Preobrazhenskii Regiment was reduced in size by one battalion, the number of flags in the regiment was reduced by five. In this same year new flags were granted to all three regiments of Guards Infantry, of the pattern established in 1800 for Army Infantry and Garrison regiments, except with double-monograms in the corners. In honorary colonels’ companies, the cross on the flag was white, the corners half puce and half white (Illus. 1263a); in the other companies there was a white cross on a puce cross, and white corners (Illus. 1263b). Along with this the color of the poles was changed, and from this time they were: in the Leib-Battalion of the Preobrazhenskii Regiment—coffee-colored, in the other battalions of the regiment—straw-colored; in the Semenovskii Regiment—black; in the Izmailovskii Regiment—white (375).
...
(375) Table of flags from 1800, located in THE SOVEREIGN EMPEROR’s Own Library in portfolio No 169, and flags prepared but never used, preserved in the St.-Petersburg Arsenal."

http://marksrussianmilitaryhistory.info/V09.html

Illus. 1263b: