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