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