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