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