The generator matrix

 1  0  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  0  1  1  1  1  1  1  0  1  1  1  1  1  1  1  1  X a*X  1  1  1  1  1
 0  1  1  a a^6*X+a^2 a^3 a^6*X+a^4 a^5 a^6*X+a^6  a a^6*X+a^2  0 a^6*X+1 a^5 a^6*X+a^4 a^6*X+a^6 a^3  1 a^6*X+1 a^5 a^6*X+1 a^6*X+a^6 a^4*X+1 a^6*X+a^2  1 X+a^5 a*X+1 a^2*X+a^5 a^5*X+a^5 a^3  0 a^4*X+1 X+a^5  1  1 a^5*X+a^4 X+a^5  a a^6*X+a^4 X+a
 0  0 a^6*X  0  X  X a^3*X  X a^2*X a^3*X a^6*X a^2*X a^2*X  0  0 a^2*X a^6*X  X  X a*X a^6*X a^3*X a^4*X a^6*X a^2*X a^3*X  X  X a^4*X a^3*X a^4*X a^4*X a^3*X a^2*X a^6*X a^2*X  0 a^4*X a^4*X a^3*X
 0  0  0  X a^6*X a^5*X a^3*X a^2*X a^5*X a^6*X a^6*X a^4*X a*X a^2*X a^5*X  0 a^4*X a^5*X a*X a^3*X a^2*X  0  X a^3*X a^3*X a^4*X a^2*X a^4*X a^5*X a^6*X a^3*X a^2*X a^5*X a^2*X a^4*X a^6*X a*X a^2*X a^6*X a^2*X

generates a code of length 40 over F8[X]/(X^2) who´s minimum homogenous weight is 256.

Homogenous weight enumerator: w(x)=1x^0+539x^256+224x^259+392x^260+504x^261+1848x^263+3045x^264+4704x^267+4200x^268+2968x^269+3864x^271+5411x^272+32928x^275+19096x^276+10472x^277+11816x^279+12509x^280+76832x^283+33656x^284+14728x^285+11144x^287+10276x^288+371x^296+343x^304+259x^312+14x^320

The gray image is a linear code over GF(8) with n=320, k=6 and d=256.
This code was found by Heurico 1.16 in 8.45 seconds.