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