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