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