One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,4)(3,7,8,6)(9,10,16,19)(11,20,15,17)(12,14,13,18)(21,23,22,24)(25,26,31,28)(27,32,29,33)(30,34,38,36)(35,39,37,40)(1,3)(2,6)(4,7)(5,8)(9,11,16,15)(10,17,19,20)(12,22,13,21)(14,23,18,24)(25,27,31,29)(26,32,28,33)(30,35,38,37)(34,39,36,40)(9,12,16,13)(10,18,19,14)(11,21,15,22)(17,23,20,24)(25,27,31,29)(26,33,28,32)(30,35,38,37)(34,40,36,39)(1,2,5,4)(3,6,8,7)(9,13,16,12)(10,14,19,18)(11,22,15,21)(17,24,20,23)(25,28,31,26)(27,32,29,33)(30,36,38,34)(35,39,37,40)(1,4,5,2)(3,7,8,6)(9,14)(10,12)(11,23)(13,19)(15,24)(16,18)(17,22)(20,21)(25,29,31,27)(26,32,28,33)(30,37,38,35)(34,39,36,40)(1,3)(2,7)(4,6)(5,8)(9,15,16,11)(10,17,19,20)(12,22,13,21)(14,24,18,23)(25,30,31,38)(26,34,28,36)(27,35,29,37)(32,39,33,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.