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