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