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