One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,6)(4,8)(5,7)(9,10,15,28,13,17,14,19)(11,16,23,29,22,31,20,33)(12,24,27,32,25,18,26,34)(21,36,35,39,37,30,38,40)(1,3,5,4)(2,6,7,8)(9,11,13,22)(10,16)(12,21,25,37)(14,20,15,23)(17,31)(18,30)(19,33)(24,36)(26,38,27,35)(28,29)(32,39)(34,40)(1,4,5,3)(2,6,7,8)(10,17)(11,20,22,23)(12,25)(16,29,31,33)(19,28)(21,35,37,38)(26,27)(30,39,36,40)(9,12,13,25)(10,18,17,24)(11,21,22,37)(14,27,15,26)(16,30,31,36)(19,34,28,32)(20,35,23,38)(29,39,33,40)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.