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