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