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