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