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